This paper considers the problem of robust stabilization of multi-input-multi-output (MIMO) nonlinear systems in the presence of mismatched time-varying uncertainties. Combining the differential geometric feedback linearization with the deterministic approach, it derives two robust stabilizing controllers, i.e. the high-gain feedback controller and the variable structure controller. These two controllers only require the knowledge of the nominal system and the bounds of the uncertainties. Therefore, they are more feasible to be implemented. Both controllers reduce the effects of arbitrarily large bounded mismatched uncertainties successfully to achieve uniform ultimate boundedness stabilization of the MIMO nonlinear time-varying uncertain systems.